Latest measurement of a proton's mass has got physicists puzzled

SOMETHING isn’t measuring up. For the second time, an extremely precise measurement of the proton’s mass is different from its recognised value.

“It looks like there is a serious flaw somewhere,” says Sven Sturm at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.

The issue first raised its head in 2015, when a team led by Edmund Myers at Florida State University measured the difference in masses of the nucleus of a helium-3 atom and a deuteron – the nucleus of a deuterium or heavy hydrogen atom – with a single proton bound to …

Article amended on
28 February 2018

We corrected the property of the protons that the researchers measured